Question

我在Web服务调用中有一条if语句，该语句始终返回false。如果其中没有单词“ VERTICALPALLETS”或“ PALLETLABELS”，我希望它返回一条错误消息。即使此字段中包含这些单词，它仍会返回错误。该查询不是我在应用程序中使用的正确查询。任何帮助深表感谢。

public bool ValidateDevice(string DeviceID, string sVersion, out string MachineID, out string MachineName, out string Plant, out string Printer1, out string Printer2, out string WrapStation, out string Location, out string sMessage)
{
    MachineID = "";
    MachineName = "";
    Plant = "";
    Printer1 = "";
    Printer2 = "";
    Plant = "";
    WrapStation = "";
    Location = "";
    sMessage = "";


    bool bTest = CheckVersion(sVersion, out sMessage);
    if (bTest == false)
    {
        sMessage = "You do not meet the minimum version requirements. Contact MIS.";
        return false;
    }


    try
    {
        SqlConnection connection = new SqlConnection(capmSADPConnectionString);
        connection.Open();

        string queryString = "select * from DATABASE";
        SqlCommand command = new SqlCommand(queryString, connection);
        command.Parameters.Clear();
        command.Parameters.AddWithValue("@DEVICEID", DeviceID);
        command.Parameters.AddWithValue("@APPID", "VTP");

        SqlDataReader reader = command.ExecuteReader();

        if (reader.HasRows == false)
        {
            email myEmail = new email();
            myEmail.SendErrorEmail("No Application Settings for VTP Device ID - " + DeviceID, "VTPError", "VTP Device Settings Error");
            sMessage = "Could not find application settings for this device. Please enter settings.";
            return false;
        }




        reader.Read();

        MachineID = reader.GetValue(0).ToString();
        MachineName = reader.GetValue(1).ToString();
        Plant = reader.GetValue(2).ToString();
        Location = reader.GetValue(3).ToString();
        Printer1 = reader.GetValue(4).ToString();
        Printer2 = reader.GetValue(5).ToString();
        WrapStation = reader.GetValue(6).ToString();

        reader.Close();
        reader = null;
        command = null;
        connection.Close();
        connection = null;

        if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) || (Location.ToUpper().Contains("PALLETLABELS") == false))
        {
            sMessage = "Please enter correct location in Application Setup and try again.";
            return false;
        }



        return true;
    }
    catch (Exception e)
    {
        sMessage = "Unable to retrieve Application Settings for VTP. Please reopen the application.";
        return false;
    }
    return true;
}

Answer 1

这里的问题与您的if语句的结构有关：

if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) || (Location.ToUpper().Contains("PALLETLABELS") == false))
{
    sMessage = "Please enter correct location in Application Setup and try again.";
    return false;
}

您在说：

If the location does not contain 'VERTICALPALLETS'
Or Else
If the location does not contain 'PALLETLABELS'

除非位置包含文本的两位，否则它将始终为真！

您需要将Or Else更改为And Also（因此将||更改为&&），因此您的代码将按预期工作。

Answer 2

使用AND

if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) && (Location.ToUpper().Contains("PALLETLABELS") == false))

更易读的替代解决方案。

if (!(Location.ToUpper().Contains("VERTICALPALLETS") || Location.ToUpper().Contains("PALLETLABELS"))

Answer 3

此行

if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) || (Location.ToUpper().Contains("PALLETLABELS") == false))

检查Location.ToUpper()不包含“ VERTICALPALLETS”还是Location.ToUpper()不包含“ PALLETLABELS”。如果Location.ToUpper()不能同时包含两者，则条件为true。相反，您想检查Location.ToUpper()是否包含其中两个：

if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) && (Location.ToUpper().Contains("PALLETLABELS") == false))
{
    //...
}

另外，多次计算ToUpper并没有多大意义，让我们只计算一次：

String upperLocation = Location.ToUpper();
if ((Location.ToUpper().Contains("VERTICALPALLETS") == false) && (Location.ToUpper().Contains("PALLETLABELS") == false))
{
    //...
}

Answer 4

听起来像是问题，除非您要查找同时包含VERTICALPALLETS PALLETLABELS的位置，否则您将一直在寻找“ false”或“ false”条件

我建议您尝试类似

if (! ( condtion1 || condition2) )
 return message

C＃if语句始终返回false

4 个答案: